In supplying a feed from a feed hopper to a feeder conduit, it is desirable that a prescribed feed rate should be maintained. A simple, conventional device for constant feed is based on feed control effected by adjusting the sectional area of a path through which the feed is sent from the feed hopper. However, such a device has a disadvantage in that the feed rate depends on the amount of the feed charge in the feed hopper. Another kind of device has been developed in which a cylinder with a rugged surface, capable of rotation, is placed horizontally within a vertical feed path from a hopper, a control plate is placed along the cylinder, and in which the feed is controlled by adjusting the interval between the cylinder and the control plate, thereby adjusting the width of the feed path, and is also controlled by forcing the feed to flow by means of the rotational force on the cylinder. This kind of device, though better than the other above-mentioned device, is still incapable of providing any satisfactory degree of constant feed; especially when plural control plates have been set within the vertical feed path for intended supply of feed to plural feeder conduits, a control of one of the control plates to narrow the corresponding path will cause more feed to flow in the direction toward the other control plates, and thus there is a mutual interaction among feed paths which prevents constant feed from being kept.